Drug interactions
Chlorthalidone + Mefenamic acid
Severity: Moderate
Chlorthalidone and Mefenamic acid: moderate interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
NSAIDs can blunt the diuretic and antihypertensive effect of thiazide-type diuretics and may impair renal function, particularly in volume-depleted or elderly patients. The potassium effects of the two drugs are opposing and unpredictable.
What this interaction means in plain words
Chlorthalidone and Mefenamic acid can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Chlorthalidone belongs to Cardiovascular; Mefenamic acid belongs to Musculoskeletal.
Why it happens
NSAID inhibition of renal prostaglandin synthesis causes sodium and water retention and reduced renal perfusion, opposing diuretic action.
What to do
Monitor blood pressure, renal function and electrolytes, including potassium. Keep the NSAID course short at the lowest effective dose and ensure adequate hydration.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Mefenamic acid
- Ketorolac intranasal + Mefenamic acid Contraindicated
- Ketorolac + Mefenamic acid Contraindicated
- Aceclofenac + Mefenamic acid Major
- Acemetacin + Mefenamic acid Major
- Acetylsalicylic acid + Mefenamic acid Major
- Alteplase + Mefenamic acid Major
Other interactions of Chlorthalidone
Frequently asked questions
Can I take Chlorthalidone with Mefenamic acid?
MediHelp rates the interaction as moderate. Chlorthalidone and Mefenamic acid can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. NSAIDs can blunt the diuretic and antihypertensive effect of thiazide-type diuretics and may impair renal function, particularly in volume-depleted or elderly patients. The potassium effects of the two drugs are opposing and unpredictable.
How serious is the interaction between Chlorthalidone and Mefenamic acid?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor blood pressure, renal function and electrolytes, including potassium. Keep the NSAID course short at the lowest effective dose and ensure adequate hydration.
What other medicines interact with Mefenamic acid?
MediHelp also lists interactions of Mefenamic acid with, for example, Ketorolac intranasal, Ketorolac, Aceclofenac. The full list is on the Mefenamic acid page.
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